251 lines
10 KiB
Markdown
251 lines
10 KiB
Markdown
# Basic usage
|
|
|
|
## Installation
|
|
|
|
To install Composer, you just need to download the `composer.phar` executable.
|
|
|
|
```sh
|
|
curl -sS https://getcomposer.org/installer | php
|
|
```
|
|
|
|
For the details, see the [Introduction](00-intro.md) chapter.
|
|
|
|
To check if Composer is working, just run the PHAR through `php`:
|
|
|
|
```sh
|
|
php composer.phar
|
|
```
|
|
|
|
This should give you a list of available commands.
|
|
|
|
> **Note:** You can also perform the checks only without downloading Composer
|
|
> by using the `--check` option. For more information, just use `--help`.
|
|
>
|
|
> ```sh
|
|
> curl -sS https://getcomposer.org/installer | php -- --help
|
|
> ```
|
|
|
|
## `composer.json`: Project Setup
|
|
|
|
To start using Composer in your project, all you need is a `composer.json`
|
|
file. This file describes the dependencies of your project and may contain
|
|
other metadata as well.
|
|
|
|
The [JSON format](http://json.org/) is quite easy to write. It allows you to
|
|
define nested structures.
|
|
|
|
### The `require` Key
|
|
|
|
The first (and often only) thing you specify in `composer.json` is the
|
|
`require` key. You're simply telling Composer which packages your project
|
|
depends on.
|
|
|
|
```json
|
|
{
|
|
"require": {
|
|
"monolog/monolog": "1.0.*"
|
|
}
|
|
}
|
|
```
|
|
|
|
As you can see, `require` takes an object that maps **package names** (e.g. `monolog/monolog`)
|
|
to **package versions** (e.g. `1.0.*`).
|
|
|
|
### Package Names
|
|
|
|
The package name consists of a vendor name and the project's name. Often these
|
|
will be identical - the vendor name just exists to prevent naming clashes. It allows
|
|
two different people to create a library named `json`, which would then just be
|
|
named `igorw/json` and `seldaek/json`.
|
|
|
|
Here we are requiring `monolog/monolog`, so the vendor name is the same as the
|
|
project's name. For projects with a unique name this is recommended. It also
|
|
allows adding more related projects under the same namespace later on. If you
|
|
are maintaining a library, this would make it really easy to split it up into
|
|
smaller decoupled parts.
|
|
|
|
### Package Versions
|
|
|
|
In the previous example we were requiring version `1.0.*` of monolog. This
|
|
means any version in the `1.0` development branch. It would match `1.0.0`,
|
|
`1.0.2` or `1.0.20`.
|
|
|
|
Version constraints can be specified in a few different ways.
|
|
|
|
Name | Example | Description
|
|
-------------- | ------------------------------------------------------------------ | -----------
|
|
Exact version | `1.0.2` | You can specify the exact version of a package.
|
|
Range | `>=1.0` `>=1.0 <2.0` <code>>=1.0 <1.1 || >=1.2</code> | By using comparison operators you can specify ranges of valid versions. Valid operators are `>`, `>=`, `<`, `<=`, `!=`. <br />You can define multiple ranges. Ranges separated by a space (` `) or comma (`,`) will be treated as a **logical AND**. A double pipe (<code>||</code>) will be treated as a **logical OR**. AND has higher precedence than OR.
|
|
Hyphen Range | `1.0 - 2.0` | Inclusive set of versions. Partial versions on the right include are completed with a wildcard. For example `1.0 - 2.0` is equivalent to `>=1.0.0 <2.1` as the `2.0` becomes `2.0.*`. On the other hand `1.0.0 - 2.1.0` is equivalent to `>=1.0.0 <=2.1.0`.
|
|
Wildcard | `1.0.*` | You can specify a pattern with a `*` wildcard. `1.0.*` is the equivalent of `>=1.0,<1.1`.
|
|
Tilde Operator | `~1.2` | Very useful for projects that follow semantic versioning. `~1.2` is equivalent to `>=1.2,<2.0`. For more details, read the next section below.
|
|
|
|
### Next Significant Release (Tilde Operator)
|
|
|
|
The `~` operator is best explained by example: `~1.2` is equivalent to
|
|
`>=1.2,<2.0`, while `~1.2.3` is equivalent to `>=1.2.3,<1.3`. As you can see
|
|
it is mostly useful for projects respecting [semantic
|
|
versioning](http://semver.org/). A common usage would be to mark the minimum
|
|
minor version you depend on, like `~1.2` (which allows anything up to, but not
|
|
including, 2.0). Since in theory there should be no backwards compatibility
|
|
breaks until 2.0, that works well. Another way of looking at it is that using
|
|
`~` specifies a minimum version, but allows the last digit specified to go up.
|
|
|
|
> **Note:** Though `2.0-beta.1` is strictly before `2.0`, a version constraint
|
|
> like `~1.2` would not install it. As said above `~1.2` only means the `.2`
|
|
> can change but the `1.` part is fixed.
|
|
|
|
> **Note:** The `~` operator has an exception on its behavior for the major
|
|
> release number. This means for example that `~1` is the same as `~1.0` as
|
|
> it will not allow the major number to increase trying to keep backwards
|
|
> compatibility.
|
|
|
|
### Stability
|
|
|
|
By default only stable releases are taken into consideration. If you would like
|
|
to also get RC, beta, alpha or dev versions of your dependencies you can do
|
|
so using [stability flags](04-schema.md#package-links). To change that for all
|
|
packages instead of doing per dependency you can also use the
|
|
[minimum-stability](04-schema.md#minimum-stability) setting.
|
|
|
|
## Installing Dependencies
|
|
|
|
To fetch the defined dependencies into your local project, just run the
|
|
`install` command of `composer.phar`.
|
|
|
|
```sh
|
|
php composer.phar install
|
|
```
|
|
|
|
This will find the latest version of `monolog/monolog` that matches the
|
|
supplied version constraint and download it into the `vendor` directory.
|
|
It's a convention to put third party code into a directory named `vendor`.
|
|
In case of monolog it will put it into `vendor/monolog/monolog`.
|
|
|
|
> **Tip:** If you are using git for your project, you probably want to add
|
|
> `vendor` into your `.gitignore`. You really don't want to add all of that
|
|
> code to your repository.
|
|
|
|
Another thing that the `install` command does is it adds a `composer.lock`
|
|
file into your project root.
|
|
|
|
## `composer.lock` - The Lock File
|
|
|
|
After installing the dependencies, Composer writes the list of the exact
|
|
versions it installed into a `composer.lock` file. This locks the project
|
|
to those specific versions.
|
|
|
|
**Commit your application's `composer.lock` (along with `composer.json`) into version control.**
|
|
|
|
This is important because the `install` command checks if a lock file is present,
|
|
and if it is, it downloads the versions specified there (regardless of what `composer.json`
|
|
says).
|
|
|
|
This means that anyone who sets up the project will download the exact
|
|
same version of the dependencies. Your CI server, production machines, other
|
|
developers in your team, everything and everyone runs on the same dependencies, which
|
|
mitigates the potential for bugs affecting only some parts of the deployments. Even if you
|
|
develop alone, in six months when reinstalling the project you can feel confident the
|
|
dependencies installed are still working even if your dependencies released
|
|
many new versions since then.
|
|
|
|
If no `composer.lock` file exists, Composer will read the dependencies and
|
|
versions from `composer.json` and create the lock file after executing the `update` or the `install`
|
|
command.
|
|
|
|
This means that if any of the dependencies get a new version, you won't get the updates
|
|
automatically. To update to the new version, use `update` command. This will fetch
|
|
the latest matching versions (according to your `composer.json` file) and also update
|
|
the lock file with the new version.
|
|
|
|
```sh
|
|
php composer.phar update
|
|
```
|
|
> **Note:** Composer will display a Warning when executing an `install` command if
|
|
`composer.lock` and `composer.json` are not synchronized.
|
|
|
|
If you only want to install or update one dependency, you can whitelist them:
|
|
|
|
```sh
|
|
php composer.phar update monolog/monolog [...]
|
|
```
|
|
|
|
> **Note:** For libraries it is not necessarily recommended to commit the lock file,
|
|
> see also: [Libraries - Lock file](02-libraries.md#lock-file).
|
|
|
|
## Packagist
|
|
|
|
[Packagist](https://packagist.org/) is the main Composer repository. A Composer
|
|
repository is basically a package source: a place where you can get packages
|
|
from. Packagist aims to be the central repository that everybody uses. This
|
|
means that you can automatically `require` any package that is available
|
|
there.
|
|
|
|
If you go to the [packagist website](https://packagist.org/) (packagist.org),
|
|
you can browse and search for packages.
|
|
|
|
Any open source project using Composer should publish their packages on
|
|
packagist. A library doesn't need to be on packagist to be used by Composer,
|
|
but it makes life quite a bit simpler.
|
|
|
|
## Autoloading
|
|
|
|
For libraries that specify autoload information, Composer generates a
|
|
`vendor/autoload.php` file. You can simply include this file and you
|
|
will get autoloading for free.
|
|
|
|
```php
|
|
require 'vendor/autoload.php';
|
|
```
|
|
|
|
This makes it really easy to use third party code. For example: If your
|
|
project depends on monolog, you can just start using classes from it, and they
|
|
will be autoloaded.
|
|
|
|
```php
|
|
$log = new Monolog\Logger('name');
|
|
$log->pushHandler(new Monolog\Handler\StreamHandler('app.log', Monolog\Logger::WARNING));
|
|
|
|
$log->addWarning('Foo');
|
|
```
|
|
|
|
You can even add your own code to the autoloader by adding an `autoload` field
|
|
to `composer.json`.
|
|
|
|
```json
|
|
{
|
|
"autoload": {
|
|
"psr-4": {"Acme\\": "src/"}
|
|
}
|
|
}
|
|
```
|
|
|
|
Composer will register a [PSR-4](http://www.php-fig.org/psr/psr-4/) autoloader
|
|
for the `Acme` namespace.
|
|
|
|
You define a mapping from namespaces to directories. The `src` directory would
|
|
be in your project root, on the same level as `vendor` directory is. An example
|
|
filename would be `src/Foo.php` containing an `Acme\Foo` class.
|
|
|
|
After adding the `autoload` field, you have to re-run `install` to re-generate
|
|
the `vendor/autoload.php` file.
|
|
|
|
Including that file will also return the autoloader instance, so you can store
|
|
the return value of the include call in a variable and add more namespaces.
|
|
This can be useful for autoloading classes in a test suite, for example.
|
|
|
|
```php
|
|
$loader = require 'vendor/autoload.php';
|
|
$loader->add('Acme\\Test\\', __DIR__);
|
|
```
|
|
|
|
In addition to PSR-4 autoloading, classmap is also supported. This allows
|
|
classes to be autoloaded even if they do not conform to PSR-4. See the
|
|
[autoload reference](04-schema.md#autoload) for more details.
|
|
|
|
> **Note:** Composer provides its own autoloader. If you don't want to use
|
|
that one, you can just include `vendor/composer/autoload_*.php` files,
|
|
which return associative arrays allowing you to configure your own autoloader.
|
|
|
|
← [Intro](00-intro.md) | [Libraries](02-libraries.md) →
|